Tagged cine magnetic resonance imaging with a finite element model can predict the severity of retrosternal adhesions prior to redo cardiac surgery
Received 9 May 2008; received in revised form 15 September 2008; accepted 27 October 2008. published online 23 February 2009.
Objective
Reoperative median sternotomy entails a risk of damaging the heart or great vessels. If the severity of retrosternal adhesion is accurately assessed before sternal re-entry, resternotomy-related complications can be prevented. The purpose of this investigation was to evaluate whether the severity of retrosternal adhesions can be accurately predicted by tagged cine magnetic resonance imaging.
Methods
Thirteen patients who were scheduled to undergo cardiac reoperation were investigated by electrocardiography-gated tagged cine magnetic resonance imaging before sternal re-entry. With the imaging data, the severity of retrosternal adhesion was scored visually on the basis of abnormality in regional myocardial motion and discordance in the tagged signals of the sternum and the myocardium. Also, with the aid of a finite element model, strain at the surface of the right ventricle was calculated on the basis of displacement of the tags on the heart over the cardiac cycle. For comparison, the adhesion severity was scored visually at the time of redo surgery by surgeons who were blinded to the preoperative assessment.
Results
The preoperative adhesion severity score, as determined visually by tagged cine magnetic resonance imaging, was correlated with the intraoperative severity score (correlation coefficient: r = 0.76, P < .01). Mean strain at the surface of the heart, as calculated preoperatively by finite element model analysis, was inversely correlated with the intraoperative adhesion severity score (r = −0.78, P < .01).
Conclusion
Tagged cine magnetic resonance imaging with a finite element model can provide an accurate quantitative assessment of retrosternal adhesions before redo cardiac surgery.
aDepartment of Cardiovascular Surgery, Graduate School of Engineering, Tohoku University, Sendai, Japan
bDepartment of Radiology, Graduate School of Engineering, Tohoku University, Sendai, Japan
cDepartment of Bioengineering and Robotics, Graduate School of Engineering, Tohoku University, Sendai, Japan
Address for reprints: Yoshikatsu Saiki, MD, PhD, Department of Cardiovascular Surgery, Graduate School of Medicine, Tohoku University, 1-1 Seiryomachi, Aoba-ku, Sendai 980-8574 Japan.
ABSTRACT